Curricular Progression for Linear Function from Primary School: Comparing the National Curricula of Four Sub-Saharan African Countries

National curricula are among the most significant variables that determine mathematics achievement. Although the number of international curriculum comparisons is increasing, studies in sub-Saharan Africa are scarce. This study aims to identify similarities and differences in curricular progression, a systematic arrangement of objectives, concepts, contents, and thinking practices tailored to each grade level to meet curriculum goals by comparing the national curricula of four sub-Saharan African countries, namely Ethiopia, Ghana, Mozambique, and South Africa, from Grades 1 to 9. This comparison is based on an analytical framework of curricular progression for linear functions, as defined in this study. Mathematics curricula in sub-Saharan Africa are considered similar; however, the results revealed the opposite. Although Ghana and South Africa are relatively similar, the approaches to linear functions differ among the four countries. Moreover, curricular progression needs improvement in all four countries. Therefore, the curricular progression of the four countries may hinder students’ understanding of linear functions.